Fast dimer diffusion near the island: A computational study

Performing atomic scale simulations, we study the diffusion of small Co clusters on Cu(111) surface in the presence of Co islands. It is revealed that mesoscopic relaxations at the island-substrate interface play an important role during the diffusion events of the clusters. The diffusion barrier of small Co clusters near the islands increases with increasing cluster size. Especially, we find that dimer diffusion near the island with B step is as fast as monomer’s, which might be responsible for the formation of dendritic shaped islands at low temperature.     

STM-mediated atom motion: a Co atom and mixed CoCu<Subscript>n</Subscript> chains on a Cu(111) surface

Performing atomic scale simulations, we study the effect of the scanning tunneling microscopy tip on atom motion on a metal surface at zero bias voltage. We concentrate on a Co atom and mixed CoCu _n (n ? 68) chains on a Cu(111) surface. It is revealed that the atom motion can be tuned by adjusting the tip-substrate distance. The change in the potential landscape induced by the tip is found to depend on the tip height. In the presence of the tip, the Co atom can freely jump from the fcc site to the hcp site or vice versa when putting the tip above the adatom at a certain height. For the mixed CoCu _n chains on the Cu(111) surface, the diffusion barrier of the end Co atom from the fcc site to the nearby hcp site increases with the increasing chain length and reaches the limit when the chain length is beyond CoCu₇ without the tip. Especially, the short chains can perform a collective motion with the help of the tip. The importance of the relaxation induced by the tip-adatom interaction is demonstrated.     

Stress Concentration Near an Elliptic Crack in the Interface Between Elastic Bodies under Steady-State Vibrations

The paper addresses the three-dimensional problem on steady-state vibrations of an elastic body consisting of two perfectly joined dissimilar half-spaces with an elliptic mode I crack located in one of the half-spaces normally to the interface. The problem is reduced to a boundary integral equation for the crack opening function. The integration domain of the equation is bounded by the crack domain, and the interaction between the crack and the interface is described by a regular kernel. The equation is solved using the mapping method. Numerical results are obtained for the case where the surfaces of the elliptic crack are subjected to harmonic loading with constant amplitude. The dependences of the stress intensity factors on the wave number are presented for various relationships among the mechanical constants that ensure the absence of near-surface waves     

Mesoscopic relaxation in homoepitaxial metal growth

We demonstrate that a size-dependent mesoscopic mismatch exists in homoepitaxy, which has a strong impact on the morphology of the islands and the substrate. Atomic scale calculations for double layer Cu islands on Cu(111) reveal that mesoscopic strain relaxations in both islands and the substrate strongly influence the shape of islands and can effect the details of atomic motion near the island.     

Effect of the long-range adsorbate interactions on the atomic self-assembly on metal surfaces

Recent experimental studies have demonstrated that short linear chains are often formed in the early stage of heteroepitaxy on the (1 1 1) noble metal surfaces at low temperatures. Here, we show that the surface-state mediated long-range interaction between adsorbates is the driving force for the self-organization of adsorbates at very low temperatures. Our kinetic Monte Carlo simulations for Co adatoms on Cu(1 1 1) and for Ce adatoms on Ag(1 1 1) reveal that these interactions can lead to the formation of linear chains.     

Interaction between cracks in a piecewise-homogeneous body

Institute of Applied Problems of Mechanics and Mathematics, Academy of Sciences of the Ukraine, L'vov. Translated from Prikladnaya Mekhanika, Vol. 28, No. 12, pp. 46–56, December, 1992.     

Ca(2+)-triggered coelenterazine-binding protein from Renilla as an enzyme-dependent label for binding assay

The recombinant Ca²⁺-triggered coelenterazine-binding protein (CBP) from Renilla muelleri was investigated as a biospecifically labeled molecule for in vitro assay applications. The protein was shown to be stable in solutions in the frozen state, as well as stable under heating and to chemical modifications. Conjugates with biotin, oligonucleotide, and proteins were obtained and applied as biospecific molecules in a solid-phase microassay. CBP detection was performed with intact (no modifications were made) Renilla luciferase in the presence of calcium, and the detection limit was found to be 75 amol. Model experiments indicate that this approach shows much promise, especially with regard to the development of multianalytical systems.